[PATCH 17/17] PM: hibernate: split and simplify hib_submit_io

Christoph Hellwig
2025-04-22T14:27:39Z

Split hib_submit_io into a sync and async version. The sync version is
a small wrapper around bdev_rw_virt which implements all the logic to
add a kernel direct mapping range to a bio and synchronously submits it,
while the async version is slightly simplified using the
bio_add_virt_nofail for adding the single range.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
kernel/power/swap.c | 103 +++++++++++++++++++-------------------------
1 file changed, 45 insertions(+), 58 deletions(-)

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 80ff5f933a62..ad13c461b657 100644
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -268,35 +268,26 @@ static void hib_end_io(struct bio *bio)
bio_put(bio);
}

-static int hib_submit_io(blk_opf_t opf, pgoff_t page_off, void *addr,
+static int hib_submit_io_sync(blk_opf_t opf, pgoff_t page_off, void *addr)
+{
+ return bdev_rw_virt(file_bdev(hib_resume_bdev_file),
+ page_off * (PAGE_SIZE >> 9), addr, PAGE_SIZE, opf);
+}
+
+static int hib_submit_io_async(blk_opf_t opf, pgoff_t page_off, void *addr,
struct hib_bio_batch *hb)
{
- struct page *page = virt_to_page(addr);
struct bio *bio;
- int error = 0;

bio = bio_alloc(file_bdev(hib_resume_bdev_file), 1, opf,
GFP_NOIO | __GFP_HIGH);
bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);
-
- if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
- pr_err("Adding page to bio failed at %llu\n",
- (unsigned long long)bio->bi_iter.bi_sector);
- bio_put(bio);
- return -EFAULT;
- }
-
- if (hb) {
- bio->bi_end_io = hib_end_io;
- bio->bi_private = hb;
- atomic_inc(&hb->count);
- submit_bio(bio);
- } else {
- error = submit_bio_wait(bio);
- bio_put(bio);
- }
-
- return error;
+ bio_add_virt_nofail(bio, addr, PAGE_SIZE);
+ bio->bi_end_io = hib_end_io;
+ bio->bi_private = hb;
+ atomic_inc(&hb->count);
+ submit_bio(bio);
+ return 0;
}

static int hib_wait_io(struct hib_bio_batch *hb)
@@ -316,7 +307,7 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
{
int error;

- hib_submit_io(REQ_OP_READ, swsusp_resume_block, swsusp_header, NULL);
+ hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block, swsusp_header);
if (!memcmp("SWAP-SPACE",swsusp_header->sig, 10) ||
!memcmp("SWAPSPACE2",swsusp_header->sig, 10)) {
memcpy(swsusp_header->orig_sig,swsusp_header->sig, 10);
@@ -329,8 +320,8 @@ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags)
swsusp_header->flags = flags;
if (flags & SF_CRC32_MODE)
swsusp_header->crc32 = handle->crc32;
- error = hib_submit_io(REQ_OP_WRITE | REQ_SYNC,
- swsusp_resume_block, swsusp_header, NULL);
+ error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
+ swsusp_resume_block, swsusp_header);
} else {
pr_err("Swap header not found!\n");
error = -ENODEV;
@@ -380,36 +371,30 @@ static int swsusp_swap_check(void)

static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb)
{
+ gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;
void *src;
int ret;

if (!offset)
return -ENOSPC;

- if (hb) {
- src = (void *)__get_free_page(GFP_NOIO | __GFP_NOWARN |
- __GFP_NORETRY);
- if (src) {
- copy_page(src, buf);
- } else {
- ret = hib_wait_io(hb); /* Free pages */
- if (ret)
- return ret;
- src = (void *)__get_free_page(GFP_NOIO |
- __GFP_NOWARN |
- __GFP_NORETRY);
- if (src) {
- copy_page(src, buf);
- } else {
- WARN_ON_ONCE(1);
- hb = NULL; /* Go synchronous */
- src = buf;
- }
- }
- } else {
- src = buf;
+ if (!hb)
+ goto sync_io;
+
+ src = (void *)__get_free_page(gfp);
+ if (!src) {
+ ret = hib_wait_io(hb); /* Free pages */
+ if (ret)
+ return ret;
+ src = (void *)__get_free_page(gfp);
+ if (WARN_ON_ONCE(!src))
+ goto sync_io;
}
- return hib_submit_io(REQ_OP_WRITE | REQ_SYNC, offset, src, hb);
+
+ copy_page(src, buf);
+ return hib_submit_io_async(REQ_OP_WRITE | REQ_SYNC, offset, src, hb);
+sync_io:
+ return hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC, offset, buf);
}

static void release_swap_writer(struct swap_map_handle *handle)
@@ -1041,7 +1026,7 @@ static int get_swap_reader(struct swap_map_handle *handle,
return -ENOMEM;
}

- error = hib_submit_io(REQ_OP_READ, offset, tmp->map, NULL);
+ error = hib_submit_io_sync(REQ_OP_READ, offset, tmp->map);
if (error) {
release_swap_reader(handle);
return error;
@@ -1065,7 +1050,10 @@ static int swap_read_page(struct swap_map_handle *handle, void *buf,
offset = handle->cur->entries[handle->k];
if (!offset)
return -EFAULT;
- error = hib_submit_io(REQ_OP_READ, offset, buf, hb);
+ if (hb)
+ error = hib_submit_io_async(REQ_OP_READ, offset, buf, hb);
+ else
+ error = hib_submit_io_sync(REQ_OP_READ, offset, buf);
if (error)
return error;
if (++handle->k >= MAP_PAGE_ENTRIES) {
@@ -1590,8 +1578,8 @@ int swsusp_check(bool exclusive)
BLK_OPEN_READ, holder, NULL);
if (!IS_ERR(hib_resume_bdev_file)) {
clear_page(swsusp_header);
- error = hib_submit_io(REQ_OP_READ, swsusp_resume_block,
- swsusp_header, NULL);
+ error = hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block,
+ swsusp_header);
if (error)
goto put;

@@ -1599,9 +1587,9 @@ int swsusp_check(bool exclusive)
memcpy(swsusp_header->sig, swsusp_header->orig_sig, 10);
swsusp_header_flags = swsusp_header->flags;
/* Reset swap signature now */
- error = hib_submit_io(REQ_OP_WRITE | REQ_SYNC,
+ error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
swsusp_resume_block,
- swsusp_header, NULL);
+ swsusp_header);
} else {
error = -EINVAL;
}
@@ -1650,13 +1638,12 @@ int swsusp_unmark(void)
{
int error;

- hib_submit_io(REQ_OP_READ, swsusp_resume_block,
- swsusp_header, NULL);
+ hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block, swsusp_header);
if (!memcmp(HIBERNATE_SIG,swsusp_header->sig, 10)) {
memcpy(swsusp_header->sig,swsusp_header->orig_sig, 10);
- error = hib_submit_io(REQ_OP_WRITE | REQ_SYNC,
+ error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,
swsusp_resume_block,
- swsusp_header, NULL);
+ swsusp_header);
} else {
pr_err("Cannot find swsusp signature!\n");
error = -ENODEV;
--
2.47.2